Preheating and sealing device for a conduit connected to the vacuum chamber of a metal degassing apparatus



NOV- 18 1959 J. v. MARslLlo ET AL 3,479,486

PREHEATING AND SEALING DEVICE FOR A CONDUIT CONNECTED To THE VACUUM CHAMBER OF A METAL DEGASSING APPARATUS Filed Nov. 14.. 1967 INVIENTORS` United States Patent O 3,479,486 PREHEATING AND SEALING DEVICE FOR A CON- DUIT CONNECTED TO THE VACUUM CHAM- BER OF A METAL DEGASSING APPARATUS Joseph V. Marsilio, Allentown, and Richard F. Relhman,

Quakertown, Pa., assignors to Bethlehem Steel Corporation, a corporation of Delaware Filed Nov. 14, 1967, Ser. No. 684,902 Int. Cl. F27d 11/00; C21c 5/42, 7/00 U.S. Cl. 219-385 2 Claims ABSTRACT OF THE DISCLOSURE A preheating and sealing device comprising a shell having refractory insulation containing heating elements secured to its interior, and which encloses in a substantially airtight manner a conduit connected to the vacuum chamber of a metal degassing apparatus, thereby heating the conduit prior to a degassing operation and sealing the conduit between degassing operations.

Background of the invention Various methods and apparatus have been devised to improved the quality of molten metal by vacuum degasication. In at least two of these, the melt enters and leaves a vacuum chamber through a conduit or conduits. One method is characterized by a single conduit which reciprocates up and down within the molten metal. In this manner, the metal is alternately drawn in and ejected from the 'vacuum chamber. Another method utilizes two conduits immersed in the molten metal. An inert gas is introduced into one of these conduits lessening the density of metal within it. This achieves a continuous process; the less dense metal flows up into the vacuum chamber, withc the metal within the other conduit flowing down from the chamber.

During a degasication operation the temperature of the metal drops due to heat lost by conduction and other causes. This limits the length of time a melt may be treated, and also requires the metal to possess a higher initial temperature than would otherwise be necessary. One practice previously employed to decrease temperature loss of the metal consists of preheating the conduit by gas ames. Another method utilizes carbon heating rods placed within the vacuum chamber.

Also, it is desirable to seal the conduits leading to the vacuum chamber between degassing operations. When sealed, leaks in the vacuum chamber may be ascertained, and a neutral atmosphere maybe maintained within the chamber, thereby prolonging the life of any carbon heating rods within it.

Summary of the invention It has been discovered that aconduit connected to the vacuum chamber of a metal degassing Iapparatus may be both sealed between degassing operations and heated prior to degassing operations by enclosing the conduit, in a substantially airtight manner, within a device having heating elements and refractory insulation.

Brief description of the drawing The drawing is an elevation view, partially in section, illustrating the invention.

3,479,486 Patented Nov. 18, 1969 ICC Description of the preferred embodiment The drawing shows the invention being utilized with a vacuum degassing apparatus having a single conduit through which the metal enters and leaves a vacuum chamber. The conduit 1, comprising refractory material secured to both surfaces of a steel tube, is connected to vacuum chamber 2 by a circular flange 3 secured, by bolts 3a, under another circular ange 4 joined to the vacuum chamber. The invention device enclosing the conduit comprises a substantially airtight metal shell 5 having refractory insulation `6 secured to its interior. Embedded with this refractory insulation are resistance heating elements 7 which surround the conduit. The preheating and sealing device shown encloses conduit 1 in a substantially airtight manner by tightly securing a circular iiange 8, joined to the metal shell 5, against circular ange 3. Swing bolts 9, pivotally connected to the metal shell 5, secure these circular anges together, yet allow the invention device to be easily installed and removed from the degassing apparatus.

Temperature loss of the molten metal being degassed is decreased by heating conduit 1 prior to the degassing operation. This preheating is accomplished by passing electric current through resistance heating elements 7.,

After the conduit has been suiiiciently heated, the invention device is removed and the degassing operation begun. The preheating and sealing device of the invention is again installed when the operation is completed. With the device enclosing the conduit in a substantially airtight manner, possible leaks in the sealed degassing apparatus may be ascertained. Also, where carbon heating rods are used within the vacuum chamber to assist in reducing temperature loss of the melt being treated, their life may be prolonged by maintaining a neutral atmosphere within the sealed chamber.

We claim:

1. In an apparatus for degassing molten metal having a vacuum chamber and a conduit connected to said chamber, a device for heating said conduit before degassing operations and sealing said conduit between degassing operations, said device comprising:

(a) a substantially airtight removable enclosure encasing said conduit and comprising an outer shell having refractory insulation secured to its interior;

(b) at least one heating element embedded within said refractory insulation;

(c) means for passing electric current through said heating element;

(d) means for removably securing` said enclosure in substantially airtight engagement with said conduit.

2. The apparatus of claim 1 wherein the outer shell in said enclosure is substantially airtight.

References Cited UNITED STATES PATENTS 3,146,288 8/1964 Gero. 3,347,538 10/1967 Sieckman.

BERNARD A. GILHEANY, Primary Examiner R. N. ENVALL, JR., Assistant Examiner 

